C. Nageli, in 1863, was the first to notice spherocrystals of the inulin type, practically indistinguishable from those of Dahlia variabilis, in alcohol-treated plants of Acetabularia mediterranea Lam., a member of the Dasycladales. The claim that these crystals are indeed composed of inulin was made by Leitgeb, in 1887, but on insufficient grounds. It was not until 1953 that du Merac succeeded in isolating 3.5 g of a clearly identified inulin as a white powder from 150 g of fresh A. mediterranea; the main criteria she applied for establishing the chemical identity of the product were its optical rotation and specific gravity combined with its ability to yield only fructose upon hydrolysis. In Dasycladus vermicularis (Scopoli) Krasser, du Merac (1955) found no inulin, although she was able to demonstrate at least 5 low-molecular-weight fructosans in addition to free fructose and traces of sucrose. In Cymopolia barbata L. Harv. she found sucrose, fructose, and at least 8 low-molecular-weight fructosans (du Merac, 1956). These results suggest that the Dasycladales form a natural order not only in a morphological-taxonomic sense, but also biochemically: they appear to be characterized by the formation of fructose-polymers as reserve-materials. However, in order to be safe, generalizations should be based on at least a fair number of representative cases. The present author has studied Batophora oerstedi J. Ag. for that reason. From this alga also, he could isolate a substance which, according to the criteria applied by du Merac, could only be inulin. In addition, however, the compound was “fingerprinted” by means of its X-ray diffraction diagram, and some of its fermentability characteristics were established. Free fructose and fructose-containing oligosaccharides are present in addition to the inulin.